Strabismus - Fundamentals of Clinical Ophthalmology.pdf

THERAPY OF STRABISMUS
good chance of not wearing spectacles as adults.
Older children with a low refractive error may also
benefit from orthoptic exercises if the strabismus
is fully controlled by optical correction.
Surgical therapy
Guidelines for surgical treatment
of strabismus
It is important to take a careful history, to
estimate visual acuity and to make measurements
of the strabismus and determine what needs to be
done. The decision must be shared with the
parents. Time needs to be spent until the parents’
expectations match the surgeon’s. Equally
important is the need to discuss with the parents
the possibility of later development of other
muscle imbalance including inferior oblique
overaction and dissociated vertical deviation. The
emergence of these after surgery may be seen by
the parents as complications, if not explained to
them beforehand. The principles of surgery must
also consider both the horizontal and the vertical
elements. In congenital (infantile) esotropia, the
results of symmetrical surgery are excellent. In the
older child, less correction can be anticipated
from symmetrical surgery than in infancy. After
the age of 4, many strabismus surgeons would
prefer asymmetric surgery particularly in those
cases where the strabismus shows incomitance or
strong fixation preference.
Preoperative evaluation
History
This should include details of the pregnancy,
birth, milestones, and family history.
Measurement
Measurement is necessary:
● of deviation in primary positions at near and
distance and in the other eight positions of
gaze
●
with and without optical correction
● of maximal deviation under complete
dissociation
●
of ductions, vergence, forced duction and
force generation testing if necessary.
Checklist
It is important first to make certain that:
●
●
●
the vision is equal
the pattern of eye movements is constant
there is no progressive underlying pathology.
Management of specific strabismus
syndromes
Amongst the presentations of strabismus in
childhood, it is important to realise the associated
mechanical restrictions and syndromes.
Duane syndrome
Duane syndrome may be associated with
other syndromes and in particular children with
Duane’s should be assessed for a defect of
hearing, skeletal anomalies and features of
Goldenhar’s syndrome. It is important to realise
the exact deficit of movement. Type I may
present with the parents expressing concern
about a convergent squint because they fail to
recognise that the basis of the convergent squint
is that one eye is unable to abduct, and the
convergent squint is produced by the healthy eye
performing a normal adduction movement. In
other directions of gaze the child may be
binocular; occasionally this is associated with an
abnormal head posture which may interfere with
school and may require treatment (Figure 7.5).
If the child is binocular, surgery should be
deferred until school age. Surgery is confined to
recession of the medial rectus in one eye and, in
severe cases, both eyes. In rare instances, where
binocular vision is not present, we have obtained
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